The present invention broadly relates to tools used in the construction and surveying industries and, more specifically, to reels for use in combination with plumb bobs. The present invention further relates to reels which fully retract and protect flexible plumb bob lines.
In surveying and construction, it is quite often necessary to establish a point, or set of points, which vertically, or laterally, align with a preexisting point (datum). To accurately establish these point(s), a tool termed a plumb bob is commonly employed. A plumb bob is basically comprised of an elongated, frusto-conically shaped, weighted member attached to one end of a flexible line (i.e., string). In practice, it is typical for a worker to hold the free end of the flexible line in vertically aligned relation above a predetermined datum such that the plumb bob is suspended slightly above the datum. The worker may, of course, adjust the positioning of the plumb bob until it becomes vertically aligned with the predetermined datum. The flexible line then becomes a vertical extension of this datum, thereby providing surveyors, and other workers who may have an obstructed view of the actual datum, with the ability to focus in on the line and make accurate lateral alignments from the datum.
In traditional plumb bobs, there are no means of housing and protecting the flexible line attached thereto. Therefore, the line is constantly being cut due to the chafing and slicing caused through contact with other tools and foreign objects. When breakage of the line occurs on the worksite, work must come to a halt until the line is replaced. If extra line was not brought to the particular location on the worksite where work was being done at the time of the breakage, an extraordinary amount of time, and therefore money, is lost until new line is found and attached to the plumb bob.
U.S. Pat. No. 3,172,205 to Gammon attempts to correct the above-identified problem by providing a reel which protects the line by retracting it into a housing when the plumb bob is not in use. The Gammon reel does protect the majority of line, but fails to adequately protect the portion of the line immediately adjacent the top surface of the plumb bob. This causes that particular portion of the line to fray and eventually break, thereby necessitating cutting a small portion of the line and retying the remaining line to the plumb bob. Due to the positioning and cooperation of the spool and line retraction mechanism, only a short amount of line can be stored on the spool and protected within the reel housing. Therefore, after the line breaks a few times, it becomes too short to be of any value, thereby rendering the reel useless.
A second problematic area which exists in this art, and has yet to be adequately addressed in the prior art is that of attaching the flexible line to a conveniently positioned structure, thereby permitting the plumb bob to dangle above a predetermined datum for an extended period of time. It is quite often necessary for a plurality of laterally aligned points to be constructed from a single datum. Therefore, after a surveyor has marked one point, he must move the transit to the next location where a mark needs to be established. Since this transfer of location takes a considerable amount of time, in order to maintain maximum consistency, the worker holding the plumb bob must remain motionless. In this situation it would be beneficial to have a feature which permits the attachment of the line to a conveniently placed structure. This feature could also be utilized in another scenario, such as in the construction of a door jamb, where the work area is confined to a small area and two workers are needed to make a set of points vertically and laterally aligned with a datum. By attaching the line to a conveniently placed structure, the second worker could be eliminated, thereby saving time and manpower.
U.S. Pat. No. 4,442,610 to Owens, Jr. provides a plumb bob holding device which is capable of being magnetically attached to any ferrous object. This attachment device is completely separate from the plumb bob and line, therefore the free end of the line must be tied to it every time it is utilized. Furthermore, since the sole means of attachment are magnetic, it is incapable of attaching to any non-ferrous object.